The massive Northeast blackout on Aug. 14 was a "preventable" failure, a U.S.-Canadian investigative report said yesterday, concluding that a major Ohio utility violated guidelines meant to protect the power grid and didn't know that its control room computer systems had stopped working two hours before the final outage.

The three-month task force investigation, headed by the Department of Energy and its Canadian counterpart, accuses FirstEnergy Corp. of Akron, Ohio, of failing to warn other control centers on the grid until it was too late.

The report also said that FirstEnergy's control room operators were not adequately trained and that the company failed to trim trees low enough to keep its transmission lines from hitting limbs, causing short circuits that tripped out crucial power lines on its system.

One power line after another went out in a chain reaction, and with each outage the heavy volume of power flowing through Ohio toward Canada and the U.S. East Coast built up on remaining lines until finally the overloading became unmanageable.

Shortly after 4:10 p.m., huge power surges swept through Michigan and then into New York, knocking out power from Manhattan to Toronto to Detroit.

The guidelines for grid operations are voluntary, and utilities that violate them are not penalized.

Energy Secretary Spencer Abraham said the blackout investigation drives home the need for operating rules, backed up by fines to punish violators.

"There need to be consequences that are well known and enforceable . . . very serious consequences," Abraham said yesterday at a news conference.

The energy bill before the Senate would impose mandatory rules and provide for penalties, and Abraham urged Congress to approved it.

Michehl Gent, president of the North American Electric Reliability Organization, which now oversees voluntary grid guidelines, said detailed audits will be made of grid control rooms around the country.

FirstEnergy's system had not been audited by his organization, he said.

The task force's findings are in line with criticism of FirstEnergy that surfaced days after the blackout.

But the Energy Department and Canadian officials heading the investigation did not examine why rules were broken or whether FirstEnergy's management had contributed to problems.

"We started to look at those issues, and then stopped," one member of the investigative team said.

Abraham said that further findings will be made after public hearings on the report are held next month in both countries. But he said the critical factor was the equipment failure that kept FirstEnergy from spotting the line outages.

"Their lack of awareness precluded them from taking the preventive steps that could have been done," Abraham said.

FirstEnergy said yesterday that the investigation had failed to take into account other disruptions on the grid outside its control.

"We believe there were hundreds of things that were abnormal on this day that have to go into the equation," said Charles E. Jones, FirstEnergy's senior vice president for delivery.

Jones said heavy loads of power being transmitted through Ohio added critically to the stress on the system, but the task force report did not agree.

The company never discussed voluntarily cutting off power to some of its customers, called "load shedding," to ease congestion on the remaining power lines, Jones said, and he questioned why FirstEnergy should have been forced to do that.

"That's another fundamental issue -- the suggestion that we should interrupt 1,500 megawatts of load to our own customers to allow the grid to make these long-distance transmissions through our system," Jones said.

The report describes the helplessness of grid operators and security coordinators whose computer systems were not operating properly, leaving them blind to the rapid deterioration of the grid.

There are no indications that computer hackers or sabotage was involved, the report said.

In one case, a technician had repaired a system earlier in the afternoon. But the technician forgot to turn on a feature that updated information every five minutes, preventing it from operating normally, the report said. "Thinking the system had been successfully restored, the analyst went to lunch," the report said.

This error at a control room of the Midwest Independent Transmission System Operator in Carmel, Ind., left it unable to track the grid's growing problems, the report said.

Another key failure involved the loss at 2:14 p.m. of alarm functions on computer systems in FirstEnergy's main control room. They monitor power conditions on its grid and are meant to alert operators to reduce overloading, the report said. With the alarms not working, operators missed readings on computer monitors that would have signaled the need to take emergency actions, the report said.

"Without a functioning alarm system, the FE [FirstEnergy] control area operators failed to detect the tripping of electrical facilities essential to maintain the security of their control area."

The loss of the alarm capability was followed by other computer malfunctions in the control room.

"However, for over an hour no one in the FE control room grasped that their computer systems were not operating properly," even though company technicians were working on the problems, the report said.

Unlike other grid control centers, FirstEnergy's does not have a computerized map board showing conditions on major lines and at power plants -- another weakness in its system, the report said.

Outside analysts studying the blackout have questioned whether FirstEnergy should have seen that its systems were malfunctioning and at least alerted others on the grid.

Jones said the company realized after about an hour that its computers weren't working as intended.

"But we had no knowledge of the extent of it," Jones said. The company sent operators to power substations to read meters on flows and report the information by telephone, but by then the situation was deteriorating too rapidly.

Abraham said that because grid guidelines were voluntary at the time of the blackout, it is not clear whether any federal action could be taken.

Ohio Gov. Bob Taft (R) has asked the state's Public Utility Commission to order FirstEnergy to upgrade its transmission maintenance and operations procedures. But state regulators' oversight covers the smaller distribution power lines within communities, not the high-voltage transmission system, which is a federal responsibility.

Energy Secretary Spencer Abraham, left, and Canadian Minister of Natural Resources Herb Dhaliwal arrive yesterday for a news conference on the joint blackout investigation.